In foundry practice, mole jackets are utilized in conjunction with sand molds during the pouring of molten metal. The sand mold is conventionally formed in mating upper and lower halves, which, in combination, define one or more cavities adapted to receive the molten metal. The outer surface of the sand mold is provided with slope or draft, and prior to pouring, a mold jacket is placed around the mold and straddles the parting line between the mold halves. In addition, a weight, in the form of a metal plate, is placed on the upper surface of the upper mold half.
The mold jacket in combination with the weight serves to prevent the upper mold half from rising relative to the lower half due to the pressure of the molten metal and thus serves to minimize run-out of the molten metal along the parting line. Nevertheless, with the use of conventional mold jackets there are instances of run-out of the molten metal, and the run-out can be a potential hazard to the operator.